Fair Value Measurement - Fair Value Level 3 Rollforward Recurring Basis (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
FG VIEs’ Assets
Fair Value Level 3 Rollforward
Fair value at beginning of period	$ 160	$ 188	$ 174	$ 204
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	2	1	(1)	0
Other comprehensive income (loss)	0	0	1	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(6)	(9)	(18)	(24)
Reclassifications	0		0
Consolidations		0
Deconsolidations		0		0
Transfers into Level 3			0
Transfers out of Level 3	0	0	0	0
Fair value at end of period	156	180	156	180
Change in unrealized gains/(losses) related to financial instruments held	0	0	(5)	(3)
FG VIEs’ Assets | Other Comprehensive Income (Loss)
Total pre-tax realized and unrealized gains (losses) recorded in:
Change in unrealized gains/(losses) related to financial instruments held			1
Consolidated Investment Vehicles | Equity Securities
Fair Value Level 3 Rollforward
Fair value at beginning of period	93	290	80
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	9	5	21
Other comprehensive income (loss)	0	0	0
Purchases	0	3	0
Sales	(3)	(4)	(5)
Settlements	0	0	0
Reclassifications	0		0
Consolidations		0
Deconsolidations		(219)
Transfers into Level 3			3
Transfers out of Level 3	(2)	0	(2)
Fair value at end of period	97	75	97	75
Change in unrealized gains/(losses) related to financial instruments held	9	6	21
Consolidated Investment Vehicles | Equity securities and warrants
Fair Value Level 3 Rollforward
Fair value at beginning of period				297
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)				45
Other comprehensive income (loss)				0
Purchases				41
Sales				(89)
Settlements				0
Deconsolidations				(219)
Transfers out of Level 3				0
Fair value at end of period		75		75
Change in unrealized gains/(losses) related to financial instruments held				6
Consolidated Investment Vehicles | Corporate securities
Fair Value Level 3 Rollforward
Fair value at beginning of period		84		96
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)		0		(3)
Other comprehensive income (loss)		0		0
Purchases		0		6
Sales		0		(15)
Settlements		0		0
Consolidations		0
Deconsolidations		(84)		(84)
Transfers out of Level 3		0		0
Fair value at end of period		0		0
Change in unrealized gains/(losses) related to financial instruments held		0		0
Consolidated Investment Vehicles | Structured products
Fair Value Level 3 Rollforward
Fair value at beginning of period	225	0	189	46
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	(5)	7	(10)	9
Other comprehensive income (loss)	0	0	0	0
Purchases	25	0	76	0
Sales	0	0	(20)	(48)
Settlements	0	0	0	0
Reclassifications	(8)		(8)
Consolidations		0
Deconsolidations		166		166
Transfers into Level 3			10
Transfers out of Level 3	0	0	0	0
Fair value at end of period	237	173	237	173
Change in unrealized gains/(losses) related to financial instruments held	(1)	7	(3)	7
Other
Fair Value Level 3 Rollforward
Fair value at beginning of period	6	33	14	50
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	(4)	(20)	(12)	(33)
Other comprehensive income (loss)	1	0	1	0
Purchases	1	0	1	0
Sales	0	0	0	0
Settlements	0	0	0	(4)
Reclassifications	0		0
Consolidations		0
Deconsolidations		0		0
Transfers into Level 3			0
Transfers out of Level 3	0	0	0	0
Fair value at end of period	4	13	4	13
Change in unrealized gains/(losses) related to financial instruments held	(4)	(20)	(12)	(33)
Other | Other Comprehensive Income (Loss)
Total pre-tax realized and unrealized gains (losses) recorded in:
Change in unrealized gains/(losses) related to financial instruments held	1	0	1	0
Financial Guaranty Variable Interest Entities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value at start of period	(393)	(699)	(554)	(715)
Total Pretax Realized And Unrealized Gains (Losses) Recorded As Liabilities [Abstract]
Net income (loss)	(3)	17	6	18
Other comprehensive income (loss)	(1)	13	(1)	14
Issuances	0		0
Settlements	5	127	157	141
Deconsolidations		0		0
Fair value at end of period	(392)	(542)	(392)	(542)
Change in unrealized gains/(losses) included in earnings related to financial instruments	(4)	9	0	11
Change in unrealized gains/(losses) included in OCI related to financial instruments	(1)	13	(1)	14
Liabilities of CIVs (9)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value at start of period		(4,199)		(4,154)
Total Pretax Realized And Unrealized Gains (Losses) Recorded As Liabilities [Abstract]
Net income (loss)		0		(45)
Other comprehensive income (loss)		0		(13)
Settlements		0		13
Deconsolidations		4,199		4,199
Fair value at end of period		0		0
Change in unrealized gains/(losses) included in earnings related to financial instruments		0		0
Change in unrealized gains/(losses) included in OCI related to financial instruments		0		0
Obligations of state and political subdivisions | Fixed-maturity securities, available-for-sale
Fair Value Level 3 Rollforward
Fair value at beginning of period	7	46	6	47
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	0	0	0	1
Other comprehensive income (loss)	0	(3)	2	(3)
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	(1)	(1)	(3)
Reclassifications	0		0
Consolidations		0
Deconsolidations		0		0
Transfers into Level 3			0
Transfers out of Level 3	0	(40)	0	(40)
Fair value at end of period	7	2	7	2
Obligations of state and political subdivisions | Fixed-maturity securities, available-for-sale | Other Comprehensive Income (Loss)
Total pre-tax realized and unrealized gains (losses) recorded in:
Change in unrealized gains/(losses) related to financial instruments held	0	0	2	0
RMBS | Fixed-maturity securities, available-for-sale
Fair Value Level 3 Rollforward
Fair value at beginning of period	150	162	154	179
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	5	4	12	11
Other comprehensive income (loss)	3	(6)	5	(14)
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(6)	(7)	(19)	(23)
Reclassifications	0		0
Consolidations		0
Deconsolidations		0		0
Transfers into Level 3			0
Transfers out of Level 3	0	0	0	0
Fair value at end of period	152	153	152	153
RMBS | Fixed-maturity securities, available-for-sale | Other Comprehensive Income (Loss)
Total pre-tax realized and unrealized gains (losses) recorded in:
Change in unrealized gains/(losses) related to financial instruments held	3	(6)	5	(13)
Asset-backed securities | Fixed-maturity securities, available-for-sale
Fair Value Level 3 Rollforward
Fair value at beginning of period	795	800	803	794
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	7	13	24	13
Other comprehensive income (loss)	(3)	(2)	5	(10)
Purchases	19	0	30	23
Sales	0	0	0	(2)
Settlements	(31)	(15)	(95)	(22)
Reclassifications	0		0
Consolidations		0
Deconsolidations		0		0
Transfers into Level 3			20
Transfers out of Level 3	0	0	0	0
Fair value at end of period	787	796	787	796
Asset-backed securities | Fixed-maturity securities, available-for-sale | Other Comprehensive Income (Loss)
Total pre-tax realized and unrealized gains (losses) recorded in:
Change in unrealized gains/(losses) related to financial instruments held	(3)	3	3	0
Contingent Value Instruments | Fixed-maturity securities, available-for-sale
Fair Value Level 3 Rollforward
Fair value at beginning of period	0		0
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	0		0
Other comprehensive income (loss)	0		0
Purchases	0		0
Sales	0		0
Settlements	(2)		(2)
Reclassifications	8		8
Transfers into Level 3			0
Transfers out of Level 3	0		0
Fair value at end of period	6		6
Change in unrealized gains/(losses) related to financial instruments held	0		0
Credit Risk Contract
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value at start of period	(34)	(57)	(50)	(162)
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	3	9	19	115
Other comprehensive income (loss)	0	0	0	0
Issuances	(2)		(2)
Settlements	(1)	(1)	(1)	(2)
Deconsolidations		0		0
Fair value at end of period	(34)	(49)	(34)	(49)
Change in unrealized gains/(losses) included in earnings related to financial instruments	$ 1	$ 9	$ 9	$ 114